I. Field of the Invention
This invention relates generally to catheters, and more particularly to an intravascular or other type of catheter having a deflectable distal tip portion to facilitate the steering thereof along a body lumen where the device used to deflect the tip comprises a guidewire.
II. Discussion of the Prior Art
In performing a variety of diagnostic and therapeutic procedures, it is known that an elongated, flexible catheter may be routed through the vascular system until a distal end thereof is disposed at a desired location where a measurement is to be taken or therapy delivered. Certain of these prior art catheters may have a preformed tip shape configuration to facilitate its routing. Others may have deflectable tips, such as is shown in U.S. Pat. No. 4,940,062 to Hampton, et al. Here, an internal pull-wire is contained within a lumen of the catheter and a distal end of the pull-wire is affixed to a closed end of the catheter. Tensioning of the pull-wire causes the distal tip portion to deflect at an angle to the longitudinal axis of the catheter where the extent of bending is a function of the amount of tension applied to the pull-wire. The catheter of the Hampton et al. patent has a closed distal end, precluding the use of a conventional guidewire to assist in routing and placement of the catheter. This is a distinct disadvantage in that most medical practitioners involved in interventional procedures routinely use elongated, flexible guide wires to assist in advancing a guide catheter through a patient's vascular system into the cardiac chamber, or into a coronary artery or vein.
Following the Seldinger technique, a percutaneous puncture may be made in a patient's groin using an introducer and dilator to gain access to the femoral artery. A guide catheter with a guidewire can then be advanced through the introducer and advanced through the femoral artery, the right or left iliac artery, the abdominal aorta to the ascending aorta coronary ostium in the descending aorta. From there, using fluoroscopic observation, a guidewire may be advanced through the guide catheter and into a selected coronary artery. Once the guidewire is so placed, a working catheter, such as an angioplasty balloon catheter, may be advanced over or along the guidewire into the selected coronary artery where a stenosis is to be dilated.
In addition to balloon angioplasty and angiography, another use of a steerable guide catheter is in the performance of transvascular myocardial revascularization (TMR). Here, a guide catheter must be routed through the vascular system with its distal end proximate a location of myocardial ischemia. Once the catheter is so positioned, a working catheter having a tip design to penetrate into myocardial tissue is advanced through the guide catheter and used to create one or more punctures into the myocardium to inject genes. Access to the myocardium may be via the left ventricle using a retrograde aortic approach or may utilize a coronary venous approach.
From the foregoing description, it is evident that a guide catheter with a steerable tip can advantageously be used to negotiate its way through the vascular system and into the cardiac chambers or coronary vessels. Such a guide catheter should, however, accommodate the use of a guidewire therewith. While the invention herein described finds application in various cardiac diagnostic and treatment procedures, such steerable catheters may also find use in addressing vascular occlusions in peripheral vessels or in placing electrical leads in the epidural space or in the brain.